What is a Gateway 3DS?

Gateway 3DS is a hardware and software solution for backing up and playing 3DS Roms.

The hardware represented by two 3DS cartrigdes (Red and Blue card) with slots for you to insert microSD cards. The software is a file called launcher.dat. As of 10 Jan 2015, the latest version of Gateway 3DS software is “Gateway Ultra 3.0 – Public Beta”.

As of writing, the Gateway 3DS allows you to:
1. Play retail cartriges from other regions
2. Partition your 3DS’s memory card into exactly 2 portions: SysNAND and EmuNAND
3. And of course, backup your retail cartridge as a ROM, and play ROMs
With each Gateway software update, more features are updated, bugs are fixed. You have to visit the official website to find out more.

What systems will it work on?
You’ll need any 2DS/3DS/3DS XL/3DSLL console with system firmware within this range: 4.5 to 9.2. You are out of luck if you don’t have a working console within this range. It will work on consoles from ALL regions (US/EUR/JAP/AUS/KR)

What does it do to my console exactly?
The inner mechanisms are not exactly known to me at this time, but it is safe to say:
1. It runs an exploit on the vulnerable system version to get it the Gateway menu.
2. In Gateway mode, you will be able to access ROMs stored on the RSD by pressing SELECT.
3. If you shutoff your system and turn it back on, it would be like you never used Gateway before.

Caveat emperor: In the past, there were people using clones of Gateway, and the offical Gateway people decided to brick all consoles running the fake Gateway cards. It seems silly to me that there’s a clone of a cloning device, and even more silly that the first clone decided to intentionally brick all consoles using the fake Gateway cards. Well anyway. You have been warned, there is a certain risk to using Gateway.

What is SysNand and what is EmuNand?
In the Gateway menu, there is an option to backup SysNand. It is highly recommended that you do a backup. Doing a backup will create a “NAND.BIN” file on your CSD, and you MUST copy a backup to your computer.

In the Gateway menu, there is also an option to format SysNand (which you should do AFTER you backup SysNand). Formatting the SysNand will split your CSD exactly into 2 portions.

If you had a 4GB CSD card, 2GB will be allocated to SysNand, and 2GB will be allocated to EmuNand. (Probably)

SysNand: The original existing system firmware version on your console.
This is the current System Version of your console. Rebooting at any time, will bring you back to SysNand. Exiting the “System settings” screen at any time will ALSO bring you back to SysNand.
Example system version: 9.2.0-21U

So why do I need two Nands for, exactly?
Gateway will only work on your console’s official system version (SysNand version 4.5 – 9.2). To put it simply: One day, there will be a 3DS game which requires SysNand version 10, and you won’t be able to play that with a Gateway. Gateway’s solution is to configure your console to have an option of updating the system firmware. Hence there is a SysNand environment and a EmuNand environment. When supported, you will be able to update EmuNand’s firmware to a supported version, so you can play new games, visit eShop, download patches.

Whenever you want to play your ROMs:
0. Put your ROMs into your CSD. (Duh)
1. Run the Gateway Exploit.
2. Press SELECT, choose a ROM, start playing.
3. To exit the ROM, press the HOME button, then A, to exit the ROM. Your save data will THEN be written onto the CSD.
4. Putting your console to sleep while playing a ROM, MAY cause your game to hang. Supposedly, this randomly happens when you sleep for more than a few hours. When in doubt, exit using step 3 before shutting down your system.